Obstructive sleep apnea (“OSA”) is a disorder characterized by repeated upper airway obstruction during sleep. OSA is a serious and life-threatening breathing disorder that affects an estimated 20 million American adults.
OSA is associated with significant adverse impacts on health and daily function including daytime sleepiness, decreases in quality of life, headaches, and serious health effects such as cardiovascular disease (hypertension, myocardial infarction, and cerebrovascular accident), endocrine disease, and death. Men, the elderly, and the obese are at elevated risk. Snoring is a related, albeit less severe, disorder that can be associated with partial airway obstruction, and it affects millions more. Therapies that treat OSA may also be effective treatments for snoring.
Current treatment methods—which range from over-the-counter oral and nasal supports to complicated surgeries—tend to be poorly tolerated and/or of limited effectiveness. These concerns may constitute barriers to diagnosis and treatment. There is a need for better OSA therapies to alleviate the suffering of individuals with OSA and also provide benefits to their families, employers, the medical infrastructure, and society at large.
The market for treatments of OSA and snoring is currently experiencing a period of unprecedented growth due both to the increasing percentage of Americans affected by the risk factors for OSA (obesity, advanced age) and to greater awareness of the conditions by medical providers and patients. As both groups have recognized the consequences of OSA and snoring, there has been a greater focus on diagnosis and treatment.
Sleep is associated with a number of physiologic changes, including the loss of upper airway muscle tone and changes in neuromuscular reflexes that can result in upper airway obstruction and snoring. In many patients with OSA and snoring, the relaxation of muscles and other changes lead to collapse of various structures around the throat and contribute to blockage of breathing and/or vibration of structures.
Current treatments for OSA and snoring include non-invasive solutions that are either only minimally effective (e.g. external nasal dilator strips or jaw-advancing appliances), efficacious but poorly tolerated (e.g. positive airway pressure therapy), or surgery (e.g. uvulopalatopharyngoplasty) that can be ineffective, invasive, costly, associated with substantial side effects, and non-reversible.
Positive Airway Pressure (“PAP”) techniques and devices are commonly used in the industry. Useful variations include BiPAP and AutoPAP. PAP is administered by means of a mechanical unit that delivers pressurized room air to the upper airway through an interface (e.g. nasal mask) that is worn by the patient during sleep. Pressurized air functions as a pneumatic splint to maintain airway patency. PAP is highly efficacious, but unfortunately long-term acceptance of this treatment and compliance are often poor. Studies have shown that between 20% and 70% of patients fail to use nasal CPAP as prescribed. Problems associated with PAP include an inability to fall asleep while wearing the device, excessive dryness of the mouth and throat, mucous congestion, sinusitis, and unconscious removal of the device during the night. Nonetheless, the market for CPAP devices is enormous and has sprouted several large companies.
One attempt to address the needs in the art teach using a magnet secured to an endotracheal tube, which is passed though the throat so that the tube can maintain a patient airway. Because the tube is subject to dislodgment, an external neckband containing a magnet was configured to attract the magnet in the tube so that tube is not subject to extubation.
Another attempt to address the needs using magnets include the use of multiple implanted magnets. Problems with prior art attempts when multiple magnets are implanted in a patient include (1) continuous force, (2) proximity will increase magnetic interaction and (3) attractive or repulsive magnetic interaction can result in migration of the magnets.
The application of continuous force may be unnecessary (cannot be readily discontinued when an apnea correction is not needed during sleep or while awake) or result in adverse consequences (for example, resulting in changes in voice or difficulty swallowing). In (2) and (3), magnetic attractive force increases as attractively oriented magnets approach each other. For magnets in soft tissue, this can lead to an accelerating process, with greater increases in attractive forces as the distance between the magnets decreases. Such attractive forces will increase the tendency of such attractive magnets to migrate, exacerbating this problem.
Other non-surgical treatments for sleep apnea include the use of mandibular repositioning devices and other oral appliances that hold and/or pull the jaw or tongue in a forward position to open the airway by reducing collapse of the soft palate, tongue, and/or other structures. These devices also suffer from uneven compliance rates and can be associated with changes in dental occlusion, dental pain, and inflammatory or degenerative changes in the temporomandibular joint.
Surgical procedures can be performed to treat OSA and snoring, and the selection is based on a number of factors, including the procedure's benefits and the individual patient's pattern of upper airway obstruction, whether at the palate and/or tongue (aka retrolingual, retroglossal, or hypopharyngeal) regions. Tracheotomy was the first OSA treatment; although highly effective, tracheotomy carries untoward social, and in some cases medical, side effects and is not performed commonly for OSA treatment. Uvulopalatopharyngoplasty (“UPPP”) is the most common procedure performed to treat OSA. The procedure involves removal of the palatine tonsils, with resection and/or repositioning of the uvula and soft palate. The procedure can increase the airway dimensions at the palate region but does not address obstruction well in the tongue region, the portion of the throat located more inferiorly.
A number of techniques and technologies have been developed to treat the tongue region. One approach utilizes radiofrequency energy to shrink and/or stiffen the soft palate and tongue. Radiofrequency energy can be used to create coagulative lesions at specific locations, and the healing process creates fibrosis and the associated tissue shrinkage and stiffening. Radiofrequency technologies can also be used to resect tongue tissue and reduce tongue size. Although effective in some, radiofrequency procedures have not performed well in the large majority of OSA patients.
Another OSA surgical approach to the tongue region is pulling the tongue anteriorly or otherwise preventing the posterior tongue prolapse that can occur with the loss of muscle tone during sleep. The most recent significant such surgical system was approved by the FDA in February 1998. Known as the tongue suspension or stabilization procedure (with the trade name Repose), it is intended to pull the tongue forward and/or stabilize the tongue in place, thereby keeping the tongue from falling into the airway during sleep. The system utilizes a bone screw inserted into the mandible. The screw attaches to a non-absorbable suture, which travels the length of the tongue and back. A similar application of this technique uses two bone screws attached to the mandible to pull the hyoid bone anteriorly and superiorly. Maxillomandibular advancement is an effective but highly invasive procedure, and the procedure's substantial morbidity and risks have limited its widespread adoption.
Techniques have also been developed for treating the soft palate with palatal implants. One attempt is a method for treating snoring of a patient, which includes embedding an implant into the patient's soft palate in order to alter the dynamic response of the soft palate to airflow. Other techniques and technologies rely on the use of chemical or thermal (including radiofrequency) injury of the soft palate to shrink and/or stiffen the palate, primarily to treat snoring but not OSA.
These treatments have demonstrated limited effectiveness and, in some cases, high morbidity, contribute to an ongoing need for more effective treatments for OSA and/or snoring.